So, is a passive house more expensive? Justin ‘Because that outside skin is going to get cold O’Connor doesn’t think so, although the research and warm we don’t want that energy to transfer is still coming in. More care does need to be taken though the insulated slab and into the building. with air tightness and with thermal breaks where So it reduces that thermal bridge,’ say Justin. surfaces meet, which can add a little time to a build. Twenty years ago when Justin O’Connor started Justin believes that the cost increase, to build a out in the building industry in Hobart, not many sustainable building in Australia is from around three people were looking for a sustainable home or per cent up to about seven per cent extra, on top of passive house. Justin had to go to Melbourne to the total cost for a standard building. learn more about them, where an international ‘We’re still gathering data – initially these types trainer provided intensive training for the Passive of buildings were mainly constructed in the high House Institute of Germany. But now demand is end of town, so it’s very hard to gauge how much growing strongly, and Justin himself is a director of extra they cost when you’re looking at million-dollar the Australian Passive House Association. builds. But we have seen really good case studies Justin only works on low-energy houses with his in Victoria, with construction of certified passive business Justin O’Connor Builders, and is currently houses for under $2000 per square metre.’ building a certified passive house for his own family. As well as airtightness, it’s important to have a ‘We keep pushing the envelope with design, and Justin O’Connor embraces new thermal break between inside and outside. So the what you can do,’ he says. techniques in passive house 45cm-thick walls have a layer of strong extruded It will be fascinating to find out the energy rating design, including the counter- polystyrene (XPS) in the middle. But otherwise the that his own home will achieve, and the air-change battened roof structure used on the Lucaston house outer wall is identical to the interior walls. rate per hour. Can he top the low-energy success ‘The outside and inside walls are unpainted – what of this Lucaston home? you see is the rammed earth,’ says Justin ‘They were ‘We’re hoping to move into that as soon as built and finished at the start of the construction.’ possible. But as builders would know, building a The earth walls were constructed from local gravel house on the weekend takes a little bit of time.’ and sand. The house has a concrete slab with It seems that this eco-builder isn’t so different to Hebel bricks around it, and the walls sit on the Hebel more traditional builders after all. bricks. This is another way to create a thermal break. www.oconnorbuilders.com.au THE HOME IS COSY AND COMFORTABLE IN WINTER, YET STAYS COOL IN LUCASTON’S WARM SUMMER 24 HOUSING MAY 2018 PROJECTS